People from Africa to Latin America are recycling bottles and using them to build fireproof, bulletproof, environmentally-friendly homes.

For about a quarter the cost of a conventional home, folks can build a two-bedroom house from 14,000 recycled plastic bottles by using the technique known as “bottle walls”.

The idea addresses both homelessness and pollution at the same time. Nigeria, for instance, has a housing shortage — 16 million people are homeless — and they have no manageable way to deal with plastic waste piling up across the country.

Nigerians have been getting help from Ecotec Environmental Solutions, a German firm since 2011, which is teaching them how to build with this model.